If you're making a voicebank with multiple pitches or multiple appends, you want to distinguish the samples from each of them, so that you can use it together. This is usually done as a suffix in the alias of the oto, so that you can add a suffix to each note in UTAU to choose different sets to use.

Is it perhaps the chorus? A lot of songs have all the choruses with the same lyrics, so the ust maker might not have bothered copy-pasting them in the ust and copy-pasted the first chorus when mixing instead.